Commercially available aluminum, fiberglass and other non-wooden arrows are usually formed in a tubular shaft configuration. Plastic nocks, adapted to be received on a bow string are attached to the rear end of such shaft. Various types of points, such as target points, field point, blunts, broadheads for hunting, fishing points, etc., are attached to the other end of the shaft to complete the arrow.
After an arrow shaft has been cut to a desired length, various structures have been utilized to attach a point to the front of the arrow shaft and a nock to the other end thereof. Typically, this attachment structure is a metal cylindrical structure adapted to be inserted into one open end of such tubular arrow and glued in place. The insert has something on it to permit attachment of the desired point or nock to it. This may be a surface to glue the point or nock thereto, but a common construction for points is a central threaded bore adapted to threadably receive a metal point body with threads formed on one end thereof.
Because the metal insert is glued to the interior of the front end of the tubular arrow shaft, usually by heat meltable glue, the outer diameter of such metal insert is not formed with close tolerances with respect to the interior diameter of the arrow shaft so that there will be room for an adequate amount of glue between the insert and the interior of the shaft. Because of this loose fit between the insert and the shaft, an alignment flange is provided on the front end of the metal insert for abutment with the extreme front annular surface of the shaft for causing the longitudinal axis of the metal insert, and thereby the longitudinal axis of a threaded bore, if present, to be in alignment with the longitudinal axis of the arrow shaft. This structure for achieving alignment works fine if the end of the shaft is cut off absolutely straight and no burrs or other irregularities are present on the extreme front end of the arrow shaft, and if adequate pressure is exerted on the insert to make sure that the alignment shoulder or flange is in abutment with the extreme end of the shaft. But as it turns out, it is a common problem that the insert is not properly seated or that shafts are not cut off straight or have metal burrs thereon, especially when such arrows are custom cut to a specific length for individual archers. Consequently, it is a common problem that arrow points sometimes arenot in alignment with the longitudinal axis of the arrow shaft, and it is well known that arrows with such a problem do not fly straight and true. For example, if a five-sixteenth inch diameter shaft is cocked one thousandth of an inch, then a point, such as on broadhead, extending three inches out therefrom is approximately eight-thousandths of an inch off center.
Accordingly, there is a need for an arrow shaft insert for attaching the front end of a tubular arrow shaft to an arrow point which will insure proper alignment irrespective of irregularities or straightness of cut on the extreme end of the arrow shaft, or whether the insert alignment flange or shoulder is properly seated against the extreme end of the arrow shaft.